where \(M\)  is the ADM mass [1]} and \(Q\)  the charge of the black hole.
We recall that, for \(M^2\ge Q^2\) , the above spacetime contains two horizons
determined by \(g^{rr}=1+2\,V_{\rm RN}=0\) , namely
\(R_\pm =G_{\rm N}\,M\pm \sqrt{G_{\rm N}^2\,M^2-G_{\rm N}\,Q^2}\ ,\) 
